401 blocks aren't that rare. Find a good one. If this was a 1930 Pierce Arrow engine I'd say fix it, but the cost of welding and sleeving your block will exceed what it will cost to replace it. As was said earlier, unless you are determined to have a numbers matching car, you need a different block.
Nothing wrong with a Cracked Nailhead in a Dragster ask me how I know:laugh: Does the crack run in a horizontal line front to back a few inches above the oil pan? If so the block froze solid.
I have a block like that,,, I welded it up,,, now I am skeered to build it,, cause , I dont trust my welding...:eek2::Brow::Brow:
I use those for expendable or short lived, high powered, frequently inspected purposes. No matter how good one is, it isn't worth getting into as an individual or small shop unless one was welding up a $10k block and had a source to a replacement, just in case. That whole market is set up differently and one needs the resources to be able to do well without such hassles.
Well, yes there are some cracks that match that description........ You should braze over the weld, put some J-B Weld onnit, and tell everyone that those bumps are vortex generators that make it more aerodynamic.. And put some stop leak in it.